A cobpobation



Dec. 18, 1928. I 1,695,422

G. w. GRISDALE ET AL ELECTRIC METER Filed Aug. 25, 1924 3 Sheets-Sheet l Dec. 18, 1928.

1,695,422 G. W. GRISDALE: ET AL ELECTRIC METER Filed Aug; 25, 1924 s sheets sheet 3 y M arv 5.;

mama pea; 18,1928.

mural) STATES PATENT: orrlcs.

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' Application and August zit-192a Serial mrsasos. Y

= This'invention relates to voltmeters of the dArsonval' galvanometer type and especithe present invention; the section being upper bearingfor the pres'entinvention ally tometers of'this type used in connection with thermo-couples for pyrometers.

The invention .has for its object the provision of a meter in which the parts ma be particularly pointed out in the appended;

claims.

In the drawin Fig. 1 is a orizontal sectional view through one form of instrument embodying taken substantially on line 1-1 of Fig. 4;

Fig. 2 is a vertical sectional view through an instrument embodying one form of the Fig. 3 is a horizontal section substantially on line 33 of Fig. 4;

Fig. 4 is a vertical section showing the galvanometer coil and .its supports onan enlarged scale; x J

Fig. 5 is a vertical 'section showing the galvanometer coil on a still-larger scale; I

Fig. .6 is afragmentary detail; and

Fig. 7 is a. fragmentarytop plan view of the galvanometer coil showin the manner of attaching the indicator nee le thereto.

The electrical measuring instrument used in connection with thermo-couples' for p?- rometers is in reality a milli-voltmeterca brated to read in de rees of temperature, the

"current being supp ied by a thermo couple which is subjected to the temperature to be measured. The voltmeterais usually of the dArsonval type, comprising acoil j'ournigled on jewel bearings between the poles of a permanent magnet. .In the present appli-' cation the invention is illustrated as applied to a meter of thewall type in whichthe magnet isarranged in. a horizontal position, but

it will be understood that the invention applicable to portable meters, recording meters, and a large variety ofother forms, as

' well "as to the trated in the drawings.

particular embodiment illus H u i ,trical connection t rough 'thespring 31 and 110' g In Figs. 1 and 2 of the drawings the permanent magnet is shown at 10 supported on a base plate 11' of non-magnetic material sew I cured to. a bracket 12 by screws 13. The.

bracket 121isillustrated as cast integrally with the back plate 14 of the meter. The magnet" 10 is rigidly clamped to the base plate 11 by a screw 15 and a clampin plate 16. 'Ad'acent its rear end the base'p ate 11 is provi ed with an upright web 17 which is I fastened to the poles 20 locking the magnet 10 also forming a supportfor the coil bracket '18. The'bracket'18 is provided with an upright T-head 19 which runs parallel with the 1 ans of the coil 26 and fits in a guide slot cut W in the rear face 'oflthe web 17, as clearly shown in Fig. The T-head 19 and the" guide therefor are-accurately machined so as to rigidly and accurately support the galvanometer coil in properly centered relation to the polepieces 20 secured to the inner faces of the rear ends of the magnet 10. The bracket 18; carries at its lower end a centrally v extending-arm 21 and at its upper end a pair of laterally curved arms 22. The-rear face. of the bracket 18 isprovided with a air oi rearwardlyprojectin lugs 23, whic have their rear faces curve to receive a cylindrical softliron core member 24. The core memher is held in place against the lugs 28 by a screw 25. The galvanometer coil 26 is supportedinposition to encircle the core 24 and to rotate about the periphery of the core and I wlthin the space between the core and the faces of thepoles 20. .This coil'is made of a number of turns of very fine wirewound upon a form which is removedafterjthe turns -'are bound toone another by a suitable binding material,'such' as shellac. [A pivot plate 27 is suitably cemented to the lower end or the coil, the plate having a pivot post 28-rigidly. securedz'thereto or formed integrally therewith. The pivot post 28 rests upon a journal screw 29 readedin the arm 21. The

screw eais provided with a jewel bearing for.

the end of the pivot post. A lock nut 30 holds the screw-29 in its adjusted positions in the arm 21. A spiral spring 31 similarto the balance spring 0;t a watch has'one and se-/' cured to the plvot post 28 and has its oppo- P site end sec'unedto a finger 32; The. finger "32gis clam ed between insulating washers33" v and a'lead wire 34 is soldered or-otherwise secured to the fin er ,32so as to make elec- 45 v ber 47 a washer 50 having upwardly bent pivot post 28 to the plate 27 Qne-end of the coil 26 is electrically connected with the plate 27 by soldering or other means so that the lead 34 is provided with electrical connection with one end ofthe coil 26. This connection entering through spring 31 is not disturbed by the rotation of the coil. The spring 31 offers resistance to rotation of the coil so as to return the coil to its zero position'after deflection due to current passing through the coil. The top end of the coil 26 i s provided with a plate 35 similar to plate27, and the opposite end of the, coil is formed rigidly -with the plate 35 and is provided with a bearing se't in'the lower end of a screw 37, The screw 37 is threaded in a sleeve 38 embedded in a bridge member 39 formed of di- I electric material. The bridge member 39 has its opposite ends supported. on the arms 22 carried by the bracket 18 A spring 40 similar to the spring '31 -is attached to the pivot pin 36 and has its opposite end secured to an upright bar 41. The bar 41 is carried at its upper end by a thermostatic spiral .42. A

lead wire 43 is'also secured to the bar 41 to 'form' the other connection for the coil 26.] The leads 34 and 43 may be carried to suitable binding posts44 atthe lower portionof the supportmg plate 14. The leads from the Q thermo-couple will be attached to the binding post 44. The thermostatic member 42, is supported on an upwardly projecting fin er 45 carried on a spring disc 46*v supporte on a zero adjustin member 47 in a manner best illustrated in provided with spring fingers 48 which resili-j ently press outwardly against a flange 49 on igs. 3 and 5f The disc 46 is the zero adjusting member 47 and surround ing the disc 46. Thisforms a spring frictional engagement between the zerovadjusting member 47 and .the disc 46 which tends to prevent relative rotation of the disc within the flange 49 but which permits stepless rotation if suflicient force is exerted. To further clamp the disc 46 to the zero adjusting mem spring tongues 51 is interposed between the bridge 39 and the'zero adjusting member 47. A washer 52 is riveted to the upper end of the sleeve 38 so that the disc 46 is clamped be tween the washer 52 and the spring tongues 51 on the washer '50. This further helps in preventing relative movement between the in'g'its upper end bifurcated, as shown in Fig,

6., The prongs 54 of the lever 53 are arranged on opposite sides of a pin 55projectzero adjusting member 47 and the disc 46,

but does not provide a rigid connection between these two parts. The member 47 is provided with a zero adjusting lever 53 having downwardly from a rotary stu 56 secured in the cover 57 for the instrument case by a screw 58, as shown on-Fig. 2. The pin 55 is arranged eceentrically on the end of the stud 56 so that when the stud is rotated the cause the finger 45 to move, which motion will be transmitted throughjhe bar 41 t0 the sprmg 40 andconsequently to the coil 26.

In this way ifthe coil is slightly. out of zero rotating the screw 56. The thermostatic member 42 is for the purpose of automatically lever 53 will ,be swung laterally. This will position the difliculty may be remedied by thus shifted they will retain their new relation because of the spring friction provided by the spring arms 48 and the spring washer 50. I 4

The coils 26 are usually made uniform for various styles of instruments and it is desi'rablegto be able to equip a coil with a number of different forms of indicating means. ;It is 5 and 7 is provided with a Pair of bridges or arches 6O struck upwardly therefrom for receiving the ends of a spring retainer plate 61. The indicator. needle 62 is provided with an enlarged portion 63 havin therein of. size to. pass over t e pivot stud 36. This enlarged 'ortion 63 rests upon the an opening {also convenient in assembling-the parts to be .able to place the needle in position indendently of the manufacture of thecoil. For this purpose the pivot plate 35.; as shown in Figs.

plate 35 and the sp ing retaining plate 61 is then moveddownwardly over the pivot pin 36.until it engages the upper face of theen:

larged portion 63. The projecting ends .64 of the retaining plate 61 are then sprung downwardly and rotated to ass beneath the bridges 60 on the plate 35. ly hold the needle. 62 in position on the 11pper end of the coil 36. The indicator may be moved ariigularly about the pin 36 against the t ue to the pressure of the retainer;

friction plate 63 to accuratel position the needle relative to the coil. A er the parts are in posi- 7 tion they are sealed against further movement by any suitable fixingis will yielding It will vbeapparent'that the coil 26 together with its supporting bearings and zero adjusting mechanism constitutes a galvanometer unit all mounted on the bracket 18,-

osit ion between the magnetic portions 20 by oosening the screw 65 and sliding the bracket 18 upwardly in the guide slot formed for the T-head 19 in the support 17. This guide slot and T-head forms a rigid support for accuratelycentering the galvanometer coil and its core relative to the pole pieces 20; and since the support extends throughout the length of the c011 and core'there' is no danger of the 1 20 and the entire "unit may be removed from its 1 parts springinilaterally to move them out of center either the exertion of external force or due to t e magnetic attraction ofthe pole pieces. The same base plate 11 which vided for the indicator 62.

I comprising a magnet having opposed pole pieces, a web'of non-magnetic material arranged adjacent said pole pieces and bridg-- ing the space between the arms of said magnet, said web being spaced from said pole pieces adjacent the central portion thereof, and a galvanometer element slidably connected with said web and movable into and out of position between said pole pieces.

2. An electrical measuring nstrument comprisin a-magnet, a web of non-magnetic material-disposed between the arms of said magnet, a pairofr pole pieces connected with the arms of said magnet adjacent said web I but spaced centrally therefrom, a galvanometer element disposed between said. pole, pieces, and a supportfor said galvanometer element, said support having alongitudinally extending T-head thereon arranged to slide within a slot in said web'sh'aped to conform to said T-head. j

3. An electrical measuring instrument comprising a magnet, a base plate of nonmagnetic material upon which said magnet is mounted, pole piecessecured to said magnet and having registering faces providing an opening therebetween, a web member bridging the space between "the arms of said magnet and extending substantially parallel 't the opening between said pole pieces, a galvanometer element slidably connected with said web member for movement into and out of said 0 ning, and a dial plate mounted on the end 0 said base plate.

4. An electri 1 measuring instrument comprising a rotary coil, a plate secured to said coil and having .a pivot pin projecting therefrom, an indicator havingan opening therein for receivingsaid'plvot p1n, a resilient lock plate having an opening-therein'for receiving pivot pin,and interengaging means on said pivot plate and lockplate' for retaining! said plates in ;position relative to one anot er to yieldinglyfsecure said indicatortosaidcoil.

.5. electrical measuring instrument comprising a rotary coil, a plvot'plate at- Y tached tosaid coil and having a pivot pin extending therefrom, said 7 plate havmg' bridge sor arches struck upwardly, an indicator having an opening therethrough for receiving said pivot pin, and a spring retaining plate having an opening therethrough for receiving said pivot pin, said retaining plate having tongues thereon for engaging beneath said bridges or arches to yieldingly lock said indicator between said pivot plate and retainer plate.

6. An electrical measuring instrument comprising a rotary coil, a zero adjusting lever for said coil, a connection between said zero adjusting lever and said coil, said connectionincluding a pair of members friction'ally held together to cause said coil and zero adjusting lever to move in unison with one another but permitting relative adjustment of said lever and coil if suflicient force 7 is exerted thereon.

7. An electrical measuring insitrurnentv comprising a rotary coil, a zero adjusting lever, for said 0011, and means for connectmg sald zero ad usting lever wlth said c011, sai

connecting means comprising a pair of discs and a spring device for holding said discs in frictional engagement with one another to constrain said coil and zero setting lever to move 1n unison but permltting relatlveiadjustment thereof.

8? An electrical measuring instrument comprising a rotary coil, a zero setting lever.

1 9; An electrical measuring instrument.

comprising a rotary coil, a zero setting lever for said co1l,'contact1ng discs connected respectively with said coil and lever, and spring means for pressing said discs together to cause them to move in unison but permitting relative adjustment thereof.

v 10. electrical measuring instrument compris ng a rotary co l, a'zero setting lever for said coil, apair of discs connected respectively with said coil and lever, one of said discs having a peripheral flange thereon-for engaging the periphery of the other of said discs while SfildlEiSt-IlflIIlGd disc is provided with sprin fingers pressing against said flange, an :s ring means for yieldingly pressing said iscs laterally against one another.

11. electrical measuring instrument comprising a magnet having opposed pole pieces, a non-magnetic bracket. secured to said magnet and spaced {from said pole pieces, and a galvanometer uni-t mounted .onsaid bracket and movable into and out of posiizo tion between said pole pieces, said galvanometer unit comprising a core member, a support for said core member slidably mounted on said bracket, arms carried by said support, pivot bearings mounted on said arms, a-coil mounted on said pivot bearings, anindicator, spring means for removably securing said indicator to said coil, a zero setting lever, and .a frictional connection between said coil and zero setting lever;

12. An electrical measuring instrument comprising a supporting plate of non-mag guide, a 'g alvanometer element carried by sald SUPPQItySfilC i element comprising a rotary 0011, an mdlcator mounted on said 0011 and havingspring means for retaining said indicator on said coil, and azero setting lever having adjustable frictional connection between said coil and lever. v

In testimony whereof we have signed our names to this specification on this 21st day of August, 1924.

GEORGE w. GRISDALE.

,ELMER SCHNEIDER. I

a gglvanometer support slidably mounted in 15 san 

